Elastic-fluid turbine.



PATENTED SEPT. 25

G. G. CURTIS.

ELASTIC FLUID TURBINE.

APPLICATION FILED D3011, 1903.

2 SHEETS-SHEBT l.

Witness es Inventor 6T No. 831,540. PATENTED SEPT. 25, I906.

G. G. CURTIS. v

ELASTIC FLUID TURBINE.

APPLICATION FILED 10110.11. 1903.

2 SHEETS-SHEET z.

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ri'nrran grapes PATENT @FFIOE.

CHARLES G CURTIS, OF YORK, Y., ASSIGNOR, BY MESNE ASSIGN- MENTS, TO GENERALELEOTRIC COMPANY, A OORPGRATION OF NEW Yoa r.

ELASTIC-FLUID TURBINE;

Patented Sept. 25, 1906.

Application filed December 11, 1903. Serial No. 184,746.

lo all whom it may concern.-

Be it known that 1, CHARLES G. CURTIS, a citizen of the United States, residing in the borough of Manhattan, city of New York, and State of New York, have-invented a certain new and useful Improvement in Elastic- Fluid Turbines,of which the following is a description.

The object-l have in view is to construct an elastic-fluid turbine in which the movable vanes have the same or approximately the same speed, specially adapted for the development of large owers at low speeds of revolution and for t e utilization of high boilerpressures, which will have the advantages arising from the employment of a large mun ber of stagesot expansion and will still have a practically low pressure in the shell of the first stage. This I accomplish by developing and utilizing in the first stage of the turbine a larger amount of energy than is developed and utilizedin any one of the subsequent stages, so as to thereby reduce the pressure in the first shell to the desiredlow pressure, the remaining energy of the elastic iluid being extracted by two or more subsequent stages, preferably in equal amounts. To secure this result, the nozzle of the first stage is made of the expansion type and has such a ratio of expansioaas will produce the desired low pressure in the first shell, while the nozzles of the subsequent stages will have a less ratio of expansion or be of the non-expansion type, the latter preferred. The pressure produced in thefirst shell may in this way be made any pressure desired. 1t is desirable that this should not be over sixty or seventypounds gage-pressure, ,which may be readily secured with an initial pressure as high as two hundred and fifty pounds gage, whereas if equal amounts of energy were developed and utilized in the several stages of a turbine having, for illustration, eight stages the pressure in the first shell would be undesirably high. Such a hi h pressure is undesirable on account of tdic bursting and distorting stress which the pressure will produce on thelarge shell area, also because of the friction loss dueto rotation of the wheel in an atmosphere of high density, and, further, because of the increased leakage through the packing around the shaft between the first shell and the next succeeding shell of the turbine. These dilliway.

'tions.

culties are overcome tion.

In the acl-mnpanying drawings, Figure 1 is a side elevation and partial section of a turby my present construcbincembodying the present invention, the

section following the line of the lluidassageand rear walls of one section of the first-stage nozzle, showing approximately its prop0r Fig. 3 is a view showing in outline the relative shape and proportions of the throat and end of the nozzle-section of Fig. 2.

Fig. 4 is a view similar to Fig. 2 of one section of the nozzles of the subsequent stages. Fig. is a view similar to Fig.3 of the nozzle-sec tion of Fig. 4, and Fig. 6 is a sectional View of theiirst four stages or a modified form 01 turbine embodying the invention.

The turbine illustrated in the drawings is one havingseven direct stages and one re- Fill. 2 is' an outline view of t 1e front verse stage. The wheels of all the stages are mounted upon a shaft A, having outsidebearings a and preferably an intermediate hearing 1), supported from a base B, from which the shells are also supported.

The seven direct stages are indicated by the letters D l) F G ll 1, while the reverse stage is represented by the letter J. The shells have outside heads c, provided with stulling boxes, through which the shaft passes, the dill'erent stages within each shell being separated from each other by diaphra ms d,.provided with sleeves, which hug the shaft closely.

K is the steam-inlet, and L is the exhaust. The last stage l of the turbine and the reyerse stage J are inthc same shell and dcliver the steam in oppositedirections into' the exhaust L, as described in my application, Serial No. 159,748, filed June 2, 1903. The nozzle .\l of the first stage is a nozzlc'ofthe expansion type, while the nozzle N of the second and each' subsequent stage has a.

lesser degree of expansion and is preferably of the non-expansion type. The nozzle of the reverse stage is of the expansion type and stage of the turbine is illustrated as provided with four sets of movable vanes and threesets of intermediate stationary vanes-al-- though if enough stages were employed and a suitable speed ofthe vanes permitted two sets, or evena single set, of movable vanes could be used in each stage or the first stage could have a plurality of sets of movable vanes and the subsequent stages a smaller number or even one set each. Such form of. turbine is illustrated in Fig. 6, in which the first stage is provided with four sets of movable vanes and the second and succeeding stages with a single set each. The wheels 1: carrying the movable vanes are. all made of the same or approximately the same diameter, and hence the vanes have the same or .ap roximately the same speed.

n Fig. 2 is illustrated on a larger scale one of the sections m of the first stage of the nozzleM in outline. For a turbine working, for I illustration, with an initial or boiler pressure of two hundred and sixty-five pounds absolutean expansion of twelve per cent. be

a pressure of about ninety-six p'ounds absolute at-the nozzle end and with the proper set of cooperating vanes a pressure in the shell of the first stage of seventy-nine pounds absolute. This pressure will be a practical one and will avoid the difiiculties already retferred to- This is the expansion intended to be re resented in Figs. 2 and 3.

' In ig. 3 the outerrectanglerepresents the size of the o ening at the end of each nozzlesection, whi e the inner rectangle represents the size of the opening at the throat, the expans'ion -'being secured by the divergence of the front and rear walls of the nozzle-sections.

In Fig. 4 is showni'in outline a section at of lthe nozzle N of the second or of any subsequent stage. The proper" thinning of -.the side walls at the outer ends of the nozzle-sections is secured by diverging the side walls; 45. but this is compensated for so as. to'give the same cross-sectional area at thethroat as at 'thenozzle' end by making the throat oblong in shape-and longer inits greater dimensions than the length of either side of the rectangle 5 0 which is -formed by the'nozzle end. This is illustrated in Fig, 5, in which the square figare represents the shape of the end of the nozzle-section and the oblong shape of the throat. -With an expansion-nozzle for the second stage, such as that illustrated inFigs.

4 and 5, and using the illustration already referred to the nozzle would receive the steam -'at seventy-nine pounds pressure absolute and wduld deliver it at about. forty-five pounds absolute, producing-a re'ssure in the shell of the'second' stage of-a out forty-two pounds-absolute. The energy thus devel- "opedan'd utilized in the second stage will be a out'one-half that developed and utilized 6 5 in'thc stage, and similarly the energy detween the throat and the nozzle end will give than in other succeeding compartments. I

veloped and utilized in [each subse uent stage will-be about one-half of that de've oped I and utilized in the first stage. The turbine with the seven direct stages is thus'equivalent to a turbine of eight direct stages inwhich the energy is divided equally between all the stages, except that in the resent instance the first stage instead of utilizing one-eighth of the total energy utilizes one-quarter of that energy, while the subsequent, stages each utilize one-eighth of the total energy.

To illustrate the actual working conditions of-a turbine of this character, I give in the h following table the pertinent data for such a machine intended to develop about twelve- 0 hundred-horse power:

Inlet Shell Throat pres' w pres- S ms of gfi Sq.ins.of St iii iii ii i res- 5 5 S 1bs.per padre end rei r p T r sq. in. qmre :g quired.

It will be understood that if a. turbine op crating with a boilerressure of two hundred and sixty-five poun s absolute and an exhaust -pressure of one pound absolute, as with theturbine illustratedin the above table, were provided with eight sta es, each de- 10 veloping and utilizing one-eight of the energy, the pressure in the firstshell would be a proximately one hundred and fifty pounds absolute, which would be an undesirably hi h pressure and would involve the difl'lre 5 cu ties alread referred to.

What I cla1m is 1.. In an elastic-fluid turbine, the combination of several stages of expansion with movable vanes having approximately the same no speed, such sta es beingconstructed so as to develo and uti ize a larger amount of energy in the 7 st stage than in any one of the two or more subsequent stages, substantially asset forth. I I

2. In an elastic-fluid turbine, the combination of several stages of expansion with movable vanes having approximately the 'same s eed, such sta es belng constructed so as to evelo and utilize a larger amount of energy x 2'0 in the i irst stage than in the one immediately following, substantially'as set forth.

3. "In an elastic -.fiuid turbine, separatecompartments, means toadmit motor fluid successively, thereto, and rotatable "buckets r2 5 ineach compartment, said buckets being arranged to cooperate withsaidmeans an abstract a" greater percentage of velocity from the motor fluid ,in an: initial compartment c 12LIIlbBIS, the nozzles for the first chamber having a greater ratio of expansion than the nozzle for any of the two or more subsequent chambers, substantially as and forth'e purpose set forth. i

--5. In an elastic-fluid turbine, the combination of several wheel-chambers connected in succession, movable vanes in each wheelchamber having ap roximately the same s eed, and nozzles for the several wheel- 0 ambers, the nozzle of the first chamber being of the expansion type and those 'of the two or more subsequent chambers being of the non-expansion type, substantially as and forthe purpose set forth.

.6. In an elastic-fluid turbine, the combination of several wheel-chambers connected in succession, two or more sets of movable vanes having approximately the same speed, and one or more sets of stationary intermediate vanes in each Wheel-chamber, and nozzles for the several wheel-chambers, the noz- \zle for the first chamber having a greater ratio of expansion than the nozzle for any of the two or more subsequent chambers, substantially as and for the purpose set forth.

7. In an elastic-fluid turbine, the combination of several wheel-chambers connected in succession, two or more sets of .movable vanes having approximately the same speed, and one or more sets of stationary interme- 'diate vanes in each wheel-chamber, and nozzles for the several wheel-chambers, the nozzle of the first chamber being of the expansion type and those of the two or more subsequent chambers being of the non-expansion type, substantially as and for the purpose set forth.

8. In an elastic-fluid turbine, the combination of several stages ofexpansion, movable vanes in each stage, an expansion-nozzle for the first stage, a non-expansion nozzle for each of the subse uent stages, two shells each divided by diap agms mto two or more chambers containing the movable vanes, outside bearings for the shaft of the turbine, and

an intermediate shaft-bearing between the two shells, substantially as set forth.

9. In an elastic-fluid turbine, the combina tion of a casing, rows of wheel-buckets, a

shaft for the wheels, and means for dividing the easing into compartments so that the high-pressure stage or stages will contaln pressurestage or stages.

10. 'In a multistage impact-turbine, stagecompartments with supply and discharge passages, and buckets cooperating with said passages, the buckets arranged in a greater number of rows in the first than in succeeding sta es.

'fhis s ecification signed and witnessed this 4th day of December, 1903.

CHARLES G. CURTIS.

Witnesses:

JNo. RoBT. TAYLOR, JOHN L. LoTscH.

'more rows of wheel-buckets than the low 

